Effect of different Neotyphodium endophytes on root distribution of a perennial ryegrass (Lolium perenne L.) cultivar

Plants of perennial ryegrass either endophyte-free or infected with Neotyphodium lolii endophyte strain AR1, AR37 or wild-type, were grown in 105-mm-diameter tubes of sand in a glasshouse. Root angles were determined by counting root intercepts on semi-circular stainless steel mesh transects running from near the edge of the tube at the sand surface to directly under the plant. The average number of root intercepts did not vary between endophyte strains or between their average and the endophyte-free treatment. However, the linear decline of root intercept frequency with depth varied according to the endophyte status of the ryegrass. Endophyte-infected plants had fewer roots close to the surface. This effect of shoot endophytes on root distribution patterns in ryegrass may improve the plant's tolerance of moisture stress.